As an example of systems for temporarily repairing a flat tire, a system has been known that has a pressure-proof container containing a puncture sealant and a high pressure air source such as a compressor (hereinafter referred also as the integrated system) (see, FIG. 1 of Patent Document 2). In this system, the puncture sealant is injected through an air valve into a tire, and then high-pressure air is continuously injected until the tire is pumped up to a sufficient pressure for driving.
Puncture sealants of this kind prepared by blending a resin tackifier and ethylene glycol with a natural rubber latex have been proposed as described in Patent Documents 1 to 3. In the case of the puncture sealants including a natural rubber latex as a base and ethylene glycol as an antifreezing agent, creaming tends to occur in a long time storage. Therefore, the storage stability (long-term storability) of the puncture sealants needs to be improved.
In order to solve the problem, Patent Document 4 has proposed a puncture sealant in which propylene glycol is used as an antifreezing agent for increasing the stability. Use of propylene glycol in place of ethylene glycol, however, may increase the viscosity of the puncture sealant at low temperatures, occasionally causing difficulties in the injection of the puncture sealant through an air valve at low temperatures. Thus, further improvement is necessary for use of a puncture sealant at substantially low temperatures. Although the fluidity of the puncture sealant can be increased by reducing the amount of the solid components such as rubber particles and a tackifying resin, the puncture sealing performance may then be deteriorated. Further, in the case that a conventional puncture sealant is employed in the integrated system, the puncture sealant may be coagulated in the air valve at high temperatures, and thus the pressure of the tire cannot be increased to a predetermined pressure level.
Patent Document 1: JP-A 2002-294214
Patent Document 2: JP-A 2001-198986
Patent Document 3: JP-A 2000-272022
Patent Document 4: JP-B 4074073